The present invention relates to a nonwoven fabric for use as a fluid transmitting topsheet for disposable diapers and sanitary napkins.
Disposable diapers, sanitary napkins and the like are generally composed of an impermeable outer covering, an absorbent core and an inner layer that is commonly referred to as a topsheet, coverstock, or in diaper applications, a diaper liner. Desirable characteristics of topsheets for such absorptive articles include rapid permeability or strike-through; a dry feeling adjacent the wearer's skin, i.e., low re-transmission of liquid from the absorbent core to the body or wearer side of the topsheet (low rewet); a soft comfortable feeling to the wearer; adequate strength; the appearance of being absorptive and a clean non-stained appearance. The subjective feel, i.e., softness and dryness, of diaper liners has become more important with the increased use of diapers by incontinent adults.
Various approaches have been attempted by the prior art to obtain a fabric having the desired characteristics for use as a diaper or sanitary napkin topsheet.
One approach was to utilize a nonwoven fabric composed of hydrophilic fibers. Although such a fabric achieved a high initial permeability, this approach suffered from the disadvantage that body fluid tended to rewet the hydrophilic fabric and thus the surface in contact with the wearer's skin stayed uncomfortably wet.
Another effort attempted to utilize an upper layer of hydrophobic fibers and a lower layer of hydrophic fibers. The disadvantage of such a fabric was the difficulty in forming the layer adjacent the skin thin enough to maintain adequate permeability yet thick enough to prevent a wet feeling to the wearer.
Another approach consisted of a nonwoven fabric comprising hydrophobic fibers containing a hydrophilic agent thereon. This fabric suffered from the disadvantage that the hydrophilic agent tends to be washed away as body fluid permeates the nonwoven fabric initially and thus it becomes difficult for body fluid to repeatedly permeate the fabric.
Another attempt has been to utilize a soft thermoplastic film having a plurality of apertures, bonded to a fibrous layer. This approach suffered from the disadvantage of low breathability and permeability for moisture generated on the wearer's skin and therefore tended to create a musty condition adjacent the wearer's skin. In addition, such a fabric suffers from a lack of softness and is not comfortable next to the wearer's skin.
Another approach has been to utilize two layers of nonwoven fabric, the first layer being in contact with the wearer's skin and comprising predominantly hydrophobic fibers with a pattern of apertures therein and a second layer bonded to the first layer composed of predominantly hydrophilic fibers with no apertures. Such a nonwoven fabric suffers from a lack of softness and thus is not comfortable to the wearer.
It is an object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which overcomes the problems of the prior art.
It is another object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which has a high permeability.
it is another object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which has low rewet properties.
It is another object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which has a high softness and thus provides a comfortable feeling to the wearer.
It is another object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which has adequate tensile strength and a cloth-like hand.
It is another object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which has the appearance of being apertured.
It is a further object of the present invention to provide a nonwoven fabric for use as a diaper or sanitary napkin topsheet which is opaque in portions of its surface and thus provides a clean and nonstained appearance when utilized as a topsheet for diapers or sanitary napkins.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.